6665433221 has 2 divisors, whose sum is σ = 6665433222. Its totient is φ = 6665433220.

The previous prime is 6665433209. The next prime is 6665433233. The reversal of 6665433221 is 1223345666.

It is a happy number.

6665433221 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a balanced prime because it is at equal distance from previous prime (6665433209) and next prime (6665433233).

It can be written as a sum of positive squares in only one way, i.e., 6504422500 + 161010721 = 80650^2 + 12689^2 .

It is a cyclic number.

It is not a de Polignac number, because 6665433221 - 2⁶ = 6665433157 is a prime.

It is a super-2 number, since 2×6665433221² = 88856000047220869682, which contains 22 as substring.

It is a nialpdrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6665433121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3332716610 + 3332716611.

It is an arithmetic number, because the mean of its divisors is an integer number (3332716611).

Almost surely, 2^6665433221 is an apocalyptic number.

It is an amenable number.

6665433221 is a deficient number, since it is larger than the sum of its proper divisors (1).

6665433221 is an equidigital number, since it uses as much as digits as its factorization.

6665433221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 38.

The square root of 6665433221 is about 81642.1044620973. The cubic root of 6665433221 is about 1881.9559789217.

Adding to 6665433221 its reverse (1223345666), we get a palindrome (7888778887).

The spelling of 6665433221 in words is "six billion, six hundred sixty-five million, four hundred thirty-three thousand, two hundred twenty-one".